1. Field
This patent specification relates to a power supplying method and apparatus, and more particularly to a power supplying method and apparatus capable of independently supplying a plurality of electric powers to respective function blocks so that, even when a problem occurs in a load or a control circuit including a CPU (central processing unit), functions relying on other electric powers that normally operate can be used as safely as possible. The patent specification further relates to a system using the power supplying method and apparatus.
2. Discussion of the Background
In recent years, digital mobile equipment such as mobile phones, digital cameras, PDAs (personal digital assistance), etc., has been provided with diverse functions. With this diversity of functions, the power supply to the functions has been required to have diverse performances and specifications. As a result, such digital mobile equipment requires a power supply circuit which supplies different kinds of electric powers having different output voltages or current capacities.
FIG. 1 illustrates a power supply circuit which supplies different kinds of electric powers and its protection circuit described in Japanese Laid-Open Patent Publication No. 2000-308332.
A power supply circuit 100 of FIG. 1 includes switching regulators 101A to 101C and a short-circuit information circuit 102. The power supply circuit 100 is connected to a load 111 and a battery 110 which is a direct-current power source. The switching regulators 101A to 101C generate and output respective predetermined voltages based on a voltage applied by the battery 110 to the load 111. Each of the switching regulators 101A to 101C has a short-circuit protection circuit (not illustrated). According to short-circuit detection signals S1 to S3 output from the switching regulators 101A to 101C, respectively, the short-circuit information circuit 102 sends a short-circuit activation signal S4 to the switching regulators 101A to 101C for causing the switching regulators 101A to 101C to perform predetermined short-circuit operations.
Each of the switching regulators 101A to 101C outputs one of the short-circuit detection signals S1 to S3 to the short-circuit information circuit 102 when its own short-circuit protection circuit monitors a corresponding power supply channel and detects an occurrence of short circuit in the power supply channel. For example, when a short circuit occurs in a power supply channel of the switching regulator 101A, a short-circuit protection circuit which protects a control IC (integrated circuit) provided in the switching regulator 101A detects the short circuit and outputs the short-circuit detection signal S1 to the short-circuit information circuit 102. Upon receipt of the short-circuit detection signal S1 input from the switching regulator 101A, the short-circuit information circuit 102 outputs the short-circuit activation signal S4 to each of the switching regulators 101A to 10C.
Upon receipt of the short-circuit activation signal S4 input from the short-circuit information circuit 102, all of the power supply channels controlled by the switching regulators 101A to 101C are subjected to short-circuit protection. For example, all of the power supply channels are brought into a power-off state in which electric supply to the load 111 is stopped. Therefore, when one of the switching regulators 101A to 101C detects the short circuit, the switching regulators 101A to 101C are placed into a predetermined short-circuit protection state, e.g., into a power-off state in which all of electric supplies to the load 110 are stopped.
In this manner, when any abnormal operation such as the short circuit is detected in the switching regulators 101A to 10C, the background power supply circuit 100 protects the switching regulators 101A to 101C and the load 111 by placing the switching regulators 101A to 101C into the power-off state to stop all electric supplies to the load 110.
As described above, in digital mobile equipment including a power supply circuit which supplies a plurality of electric powers by using a battery as a power supply, a control circuit including a CPU for controlling the equipment performs a control operation to extend a battery life by placing a circuit of a temporarily unused function into a stand-by state or by stopping electric supply to the circuit. In this manner, electric supplies to the plurality of power supply circuits are frequently performed or stopped by the control circuit in the equipment.
As in the above case, if all of the electric supplies are stopped upon detection of the abnormal operation by one of the power supply circuits, however, other functions including a protective operation function connected to other normally-operating power supply circuits also become unusable.